He may just be hinting at a brief glimpse of Smaug in the film--say in a flashback to his attack and occupation of Erebor. Even if AUJ does end with a brief shot of Smaug's eye, we could still get such a flashback. 'Thus spake Ioreth, wise-woman of Gondor: The hands of the king are the hands of a healer, and so shall the rightful king be known.' - Gandalf the White